docs: Rework of "Getting Started" section #135

Job	Run time
std::format none C++20 Clang-18 Release	6m 44s
std::format none C++20 Clang-18 Debug	6m 4s
std::format none C++23 Clang-18 Release	6m 26s
std::format none C++23 Clang-18 Debug	5m 51s
std::format gsl-lite C++20 Clang-18 Release	6m 35s
std::format gsl-lite C++20 Clang-18 Debug	6m 23s
std::format gsl-lite C++23 Clang-18 Release	6m 24s
std::format gsl-lite C++23 Clang-18 Debug	6m 18s
std::format ms-gsl C++20 Clang-18 Release	6m 42s
std::format ms-gsl C++20 Clang-18 Debug	6m 12s
std::format ms-gsl C++23 Clang-18 Release	6m 26s
std::format ms-gsl C++23 Clang-18 Debug	6m 20s
fmtlib none C++20 Clang-18 Release	6m 35s
fmtlib none C++20 Clang-18 Debug	6m 20s
fmtlib none C++23 Clang-18 Release	6m 35s
fmtlib none C++23 Clang-18 Debug	6m 3s
fmtlib gsl-lite C++20 Clang-18 Release	6m 37s
fmtlib gsl-lite C++20 Clang-18 Debug	6m 18s
fmtlib gsl-lite C++23 Clang-18 Release	6m 25s
fmtlib gsl-lite C++23 Clang-18 Debug	6m 12s
fmtlib ms-gsl C++20 Clang-18 Release	6m 46s
fmtlib ms-gsl C++20 Clang-18 Debug	6m 33s
fmtlib ms-gsl C++23 Clang-18 Release	6m 48s
fmtlib ms-gsl C++23 Clang-18 Debug	6m 14s
	2h 33m 51s

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